Ask HN: What are the most useful design resources and tools you use regularly?

Could you recommend some useful, valuable, helpful design resources that you've been using for a while and that you find extremely helpful in your workflow? Some time-savers and handy little resources such as these ones

http://tableizer.journalistopia.com

http://fontsinuse.com

http://darkpatterns.org

http://scr.im

would be very appreciated.